Advancing age is associated with the development of vascular dysfunction and disease. However, the mechanisms involved are incompletely understood. One novel and largely unexplored hypothesis is that "physiological resistance" to the adverse effects of common environmental factors to which we are chronically exposed decreases with aging, thus exacerbating the resulting dysfunction and increased risk of disease. One such factor may be a "Western", i.e., high-fat, diet (WD). The overall goal of this project is to examine the mechanisms by which WD exacerbates age-associated vascular endothelial dysfunction. Specifically, we will examine the effect of WD on signaling pathways involved in the regulation of vascular inflammation, oxidative stress and apoptosis in middle-aged (MA) and older (O) mice. The specific aims are (1) to measure endothelium dependent dilation (EDD) and nitric oxide (NO) bioavailability in the carotid arteries of MA/O mice, to determine if advancing age is associated with a pro- inflammatory, pro-oxidative, pro-apoptotic phenotype, (2) to determine if WD increases the activation of the pro-inflammatory and apoptotic signaling molecules;nuclear factor kappa B (NFkB), c-jun NH2 terminal kinase (JNK), and forkhead box O (FoxO) in MA/O mice and (3) to determine if inhibition of NFkB or JNK can reverse WD-associated vascular dysfunction, inflammation, oxidative stress and apoptosis in MA/O mice. To do so, we will study young (Y: 6-8 mo), MA (18-20 mo) and O (30-32 mo) male B6D2F1 mice. Mice will be fed standard chow (NCD, 12% kcal from fat) or a custom WD (40% kcal from fat). Vascular endothelial function will be measured in isolated carotid arteries. Nitric oxide bioavailability and activation of NFkB, JNK and FoxO will be assessed in aortic lysates. Lastly, we will utilize pharmacological inhibition of NFkB and JNK to determine their roles in WD-associated vascular endothelial dysfunction, inflammation, oxidative stress and apoptosis in MA/O mice. The expected results will provide novel insight into the mechanisms by which WD exacerbates age-associated vascular dysfunction. PUBLIC HEALTH RELEVANCE: Advancing age and consumption of a WD are associated with vascular dysfunction and disease. This proposal aims to determine if the adverse effects of WD become greater with advancing age and the mechanisms by which this may occur.